Unique Timestamp for every request

Hello All ,
I am Doing an execution which requires unique timestamp for every calls in ‘yyyyMMddHHmmss’ format which is to be passed in content body of every request.
Think time between the requests vary and I need current timestamp when that particular request hits the server.
I have tried a timestamp solution which is available in one of group discussions . But it will generate timestamp only once.
All types of suggestions are welcome.